Stresses on penstock supported by ring girder

[Zohra]

the penstocks are either supported on the saddles or on ring girder legs. the standards ( like ASME) make the calculation of the stresses on the ring girder without giving the dimension of the support leg , whereas I think that the change of the dimensions of the leg will probably change the stresses on penstock and ring . can someone enlighten me on this point please ?

 

[anorlunda]

To question the rationale and assumptions of ASME codes, you need to ask the ASME committee members. That's very difficult.

But you too did not give the dimensions of the support legs, so how can you conclude that they will change dimensions?

It may also be true that other places in the ASME standards cover supports and overall calculation strategy.

 

[anorlunda]

I had second and third thoughts on your penstock question.

2. If the supports compress a small amount, the penstock will simply bend and the load on the supports won't change much. Bending moments in the penstock could become a more critical calculation than loads on the supports.

3. Deformation of the supports may be small compared to sag of the penstock at high temperatures, or snow/ice loading, or ground settling, or geological deformations in the bedrock over the life of the dam.

 

[Zohra]

yes I was not clear in my question, I meant that standards have given formulas that calculate the stresses on the ring girder without taking into account the dimensions of leg. I want to make a CAD of the penstock to do numerical analysis and I do not know which length to give to the leg to meet the results given by the formulas. But since the load on the supports wont't change much so so no matter their size thank you so much ! maybe I have to remove the legs from the CAD for the numerical analysis and model the legs only by a fixed point ? Thank you for your support
(it is translated from french so sorry for the errors )